Biomedical Engineering Reference
In-Depth Information
Figure 3.
Diagram of typical dual-color microarray experiment. The cDNA pre-
pared from two samples to be compared (e.g. cancer cells versus normal cells) and
that are labeled with two different fluorescent dyes, namely Cy3 (O
em
570 nm) and
Cy5 (O
em
670 nm). The two Cy-labeled cDNA samples are mixed and hybridized to
a single microarray that is then scanned in a microarray scanner. Relative intensities
of each fluorophore may then be used in ratio-based analysis to identify
up-regulated and down-regulated genes.
sponding DNA array. After hybridization, a scanning fluorescence
microscope illuminates each DNA feature or spot and measures the
fluorescence from each dye separately. The yellow-colored spot
means that the particular gene can be equally expressed in both
disease and normal cells, as indicated by the additive color mixing
caused by the labeled cDNA binding. Other coloring observations
represent the presence of either downregulation or upregulation in
the corresponding cells. Ratio-based analysis of the relative inten-
sities of each fluorophore quantifies this.
3.
Sequencing by Hybridization
Current advanced modern instrumental analytical techniques can
sequence genome DNAs most efficiently. However, sequencing of
megabase to gigabase quantities of DNA still requires significant
Search WWH ::
Custom Search